Two Glasses of Water Before Eating: The Simplest Intervention Backed by Randomised Trials

No supplement, no subscription, no deprivation — one free intervention supported by randomised controlled trials.

What did the trials find?

A randomised controlled trial over 12 weeks found that people who drank 500 ml of water thirty minutes before main meals lost 1.3 kg more than the control group^[1]. A review of the evidence documented three studies showing greater weight loss with about 500 ml before a meal^[2]. And acutely, a study showed that drinking water immediately before a meal reduces voluntary food intake^[3].

Why does it work?

Two simple reasons: partial gastric filling reduces the amount consumed, and it corrects a common confusion between thirst and hunger — we often "feel hungry" while thirsty, especially in our climate.

An important Gulf point

High heat and constant air conditioning raise fluid loss without our noticing. Yet our water intake remains below requirements and is often replaced by coffee, tea and sweetened drinks — liquid calories that go uncounted. (Details on sweetened drinks in the tax article.)

How to apply it

• Two glasses (about 500 ml) before lunch and dinner — start with two meals, not three.
• Anchor it to an existing habit: after ablution for the noon prayer, for instance — linking to an established habit works better than reminders.
• Cold or warm makes no difference: volume and timing are what matter.